The present invention is related to recording data onto an optical storage medium, and more particularly, to a data recording method and apparatus with buffer management capability for re-verifying recorded data on an optical storage medium (e.g., an optical disc).
In general, when an optical storage apparatus, such as an optical disc drive, accomplishes writing a portion of user data onto a storage medium, such as an optical disc, the optical storage apparatus will verify the correctness of the recorded portion of user data, recorded onto the storage medium in the latest recording operation, according to the portion of user data which is still buffered in a buffer. In other words, a plurality of recording operations and a plurality of corresponding verifying operations are involved in one recording procedure of the optical storage medium. Assume that the portion of user data includes a plurality of ECC blocks. When a specific ECC block recorded on the optical storage medium is verified to be defective, a conventional defective block management is enabled to find a spare block on the optical storage medium for storing the specific ECC block. After the verifying operation of the portion of user data is completed, another portion of user data is received and then overwrites the portion of user data originally buffered in the buffer, and the optical storage apparatus starts a next recording operation for new data buffered in the buffer.
However, an optical pick-up head of the optical storage apparatus may slip to an erroneous address on the optical storage medium when performing a recording operation. In other words, a fatal recording error may occur during the recording operation. For example, due to power transient from read power to write power and/or servo condition variation, the optical pick-up head may slip to an erroneous address in the beginning of one recording operation. In addition, after the optical pick-up head starts the recording operation, the optical pick-up head may slip to an erroneous address due to insufficient control of a sled on which the optical pick-up head is disposed. Moreover, regarding a DVDRAM disc with wobbled land and groove tracks used for recording data, the optical pick-up head may slip to an erroneous address at a switching point between a land track and a groove track. As the fatal recording error is detected only when the optical pick-up head has slipped to an erroneous address, the write power of the optical pick-up head may damage data recorded on the optical storage medium, which degrades the data recording quality.
Please refer to FIG. 1A and FIG. 1B, which are diagrams illustrating conventional operations of verifying recorded data on an optical disc and recording data onto the optical disc, respectively. Assume that data units for data storage on the optical disc are ECC blocks, and six ECC blocks are recorded in one recording operation. As shown in FIG. 1A, ECC blocks (N−6), . . . , (N−1) are recorded onto the optical disc in one recording operation, where ECC blocks (N−6), . . . , (N−2) recorded on the optical disc have been verified in order, and the ECC block (N−1) recorded on the optical disc is under verification now. Therefore, as the recorded ECC blocks (N−6), . . . , (N−2) on the optical disc have been verified, ECC blocks (N−2), . . . , (N−6) originally buffered in the buffer are overwritten by ECC blocks N, . . . , (N+4) to be recorded onto the optical disc in the next recording operation. After the correctness of the recorded ECC block (N−1) on the optical disc has been verified, the ECC block (N−1) in the buffer is overwritten by an ECC block (N+5) to be recorded onto the optical disc in the next recording operation. As shown in FIG. 1B, the buffer stores ECC blocks N, . . . , (N+5) after the verifying operation of recorded ECC blocks (N−6), . . . , (N−1) is completed. Next, the optical disc drive starts a new recording operation to record buffered ECC blocks N, . . . , (N+5) in the buffer onto the optical disc. Assume that the optical pick-up head slips to an erroneous address at a recording start point of recording the ECC block N onto the optical disc. As can be seen from FIG. 1B, the optical pick-up head moves backwards to an address where a previously recorded and verified ECC block (N−2) is located, and the laser beam emitted by the optical pick-up head may damage the data content of the recorded ECC block (N−2). As the buffer only stores ECC blocks N, . . . , (N+5), the defective ECC block N can be successfully detected during a verifying operation, but the verifying operation fails to identify the damaged ECC block (N−2) which has been verified during a previous verifying operation. As a result, no defective block management will be applied to the damaged ECC block (N−2), and the correct data content of the ECC block (N−2) cannot be reproduced from the optical disc.